Zoom lenses used in television cameras for broadcasting need to satisfy certain conditions associated with the use of a solid-state image pickup device, such as a CCD, and at the same time they need to have high performance over the entire range of zoom, the entire range of focusing, and over the entire image plane. In addition, there is an increasing demand for zoom lenses with high magnification, very large zoom ratios and very wide, wide-angle views.
Japanese Laid-Open Patent Application 2001-183584, for example, has been proposed to meet these requirements. The zoom lens of this Japanese patent application consists of four lens groups, namely, in order from the object side, a focusing lens group, a variator lens group, a compensator lens group, and a relay lens group, and has a zoom ratio of 66 and a field angle of 58°.
However, the zoom lens of this Japanese patent application does not meet the need for a zoom lens with a zoom ratio larger than 90 that has developed in recent years. Also, the zoom lens of this Japanese patent application does not meet the need for angles of view that are wider than those of conventional wide-angle zoom lenses. These needs are expected to be met without sacrificing high optical performance anywhere within the entire range of zoom, within the entire range of focus, or over the entire image plane. As state-of-the-art broadcasting systems such as high definition broadcasting systems become more common, aberrations and fluctuations in aberrations at the telephoto end during zooming and due to focusing especially need to be minimized. Among aberrations, on-axis chromatic aberration, spherical aberration and the fluctuations in the absolute values of the aberrations must be minimized or it becomes very difficult to obtain high resolution imaging.